//// Copyright 2017 The go-ethereum Authors
//// This file is part of the go-ethereum library.
////
//// The go-ethereum library is free software: you can redistribute it and/or modify
//// it under the terms of the GNU Lesser General Public License as published by
//// the Free Software Foundation, either version 3 of the License, or
//// (at your option) any later version.
////
//// The go-ethereum library is distributed in the hope that it will be useful,
//// but WITHOUT ANY WARRANTY; without even the implied warranty of
//// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
//// GNU Lesser General Public License for more details.
////
//// You should have received a copy of the GNU Lesser General Public License
//// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
//
////go:build !nacl && !js && cgo && !gofuzz
//// +build !nacl,!js,cgo,!gofuzz
//
package crypto
//
//import (
//	"crypto/ecdsa"
//	"crypto/elliptic"
//	"fmt"
//
//	"github.com/ethereum/go-ethereum/common/math"
//	"github.com/ethereum/go-ethereum/crypto/secp256k1"
//)
//
//// Ecrecover returns the uncompressed public key that created the given signature.
//func Ecrecover(hash, sig []byte) ([]byte, error) {
//	return secp256k1.RecoverPubkey(hash, sig)
//}
//
//// SigToPub returns the public key that created the given signature.
//func SigToPub(hash, sig []byte) (*ecdsa.PublicKey, error) {
//	s, err := Ecrecover(hash, sig)
//	if err != nil {
//		return nil, err
//	}
//
//	x, y := elliptic.Unmarshal(S256(), s)
//	return &ecdsa.PublicKey{Curve: S256(), X: x, Y: y}, nil
//}
//
//// Sign calculates an ECDSA signature.
////
//// This function is susceptible to chosen plaintext attacks that can leak
//// information about the private key that is used for signing. Callers must
//// be aware that the given digest cannot be chosen by an adversery. Common
//// solution is to hash any input before calculating the signature.
////
//// The produced signature is in the [R || S || V] format where V is 0 or 1.
//func Sign(digestHash []byte, prv *ecdsa.PrivateKey) (sig []byte, err error) {
//	if len(digestHash) != DigestLength {
//		return nil, fmt.Errorf("hash is required to be exactly %d bytes (%d)", DigestLength, len(digestHash))
//	}
//	seckey := math.PaddedBigBytes(prv.D, prv.Params().BitSize/8)
//	defer zeroBytes(seckey)
//	return secp256k1.Sign(digestHash, seckey)
//}
//
//// VerifySignature checks that the given public key created signature over digest.
//// The public key should be in compressed (33 bytes) or uncompressed (65 bytes) format.
//// The signature should have the 64 byte [R || S] format.
//func VerifySignature(pubkey, digestHash, signature []byte) bool {
//	return secp256k1.VerifySignature(pubkey, digestHash, signature)
//}
//
//// DecompressPubkey parses a public key in the 33-byte compressed format.
//func DecompressPubkey(pubkey []byte) (*ecdsa.PublicKey, error) {
//	x, y := secp256k1.DecompressPubkey(pubkey)
//	if x == nil {
//		return nil, fmt.Errorf("invalid public key")
//	}
//	return &ecdsa.PublicKey{X: x, Y: y, Curve: S256()}, nil
//}
//
//// CompressPubkey encodes a public key to the 33-byte compressed format.
//func CompressPubkey(pubkey *ecdsa.PublicKey) []byte {
//	return secp256k1.CompressPubkey(pubkey.X, pubkey.Y)
//}
//
//// S256 returns an instance of the secp256k1 curve.
//func S256() elliptic.Curve {
//	return secp256k1.S256()
//}
